<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <link rel="stylesheet" href="css/bootstrap.min.css">
    <script src="js/jquery-3.4.1.min.js"></script>
    <script src="js/bootstrap.bundle.min.js"></script>
    <script src="js/bootstrap.min.js"></script>
    <style>
        div {
            border: 1px solid;
        }
    </style>
</head>

<body>
    <div class="container">
        <div class="row">
            <div class="col-1">1</div>
            <div class="col-1">2</div>
            <div class="col-1">3</div>
            <div class="col-1">4</div>
            <div class="col-1">5</div>
            <div class="col-1">6</div>
            <div class="col-1">7</div>
            <div class="col-1">8</div>
            <div class="col-1">9</div>
            <div class="col-1">10</div>
            <div class="col-1">11</div>
            <div class="col-1">12</div>
        </div>
        <div class="row">
            <div class="col-5">5</div>
            <div class="col-5">5</div>
            <div class="col-2">2</div>
        </div>
        <!-- 
            第一行：4个格子
            第二行：8个格子
            第三行：6个格子
            多出的6个格子跑到第二行去了
         -->
        <div class="row">
            <div class="col-4">4</div>
            <div class="col-8">8</div>
            <div class="col-6">6</div>
        </div>


    </div>

    <div class="container">
        <!-- 
            嵌套布局
        -->
        <div class="row">
            <div class="col-4">4</div>
            <div class="col-8">
                <!-- 
                    对于8个格子，还可以划分为12份
                 -->
                <div class="row">
                    <div class="col-3">3</div>
                    <div class="col-9">9</div>
                </div>
            </div>
        </div>
    </div>

    <div class="container">
        <div class="row">
            <div class="col-4">4</div>
            <div class="col-8">
                <div class="row">
                    <div class="col-1">1</div>
                    <div class="col-1">2</div>
                    <div class="col-1">3</div>
                    <div class="col-1">4</div>
                    <div class="col-1">5</div>
                    <div class="col-1">6</div>
                    <div class="col-1">7</div>
                    <div class="col-1">8</div>
                    <div class="col-1">9</div>
                    <div class="col-1">10</div>
                    <div class="col-1">11</div>
                    <div class="col-1">12</div>
                </div>
            </div>
        </div>
    </div>

</body>

</html>